Catalytic steam gasification of pig compost for hydrogen-rich gas production in a fixed bed reactor

Experimental and thermodynamic study of banana peel non-catalytic gasification characteristics

The Gasification performance of banana peel was examined in a fixed bed reactor. Effect of temperature, steam to carbon ratio (S/C), drying treatment on syngas composition, gas yield, CO₂ selectivity and carbon conversion efficiency (CCE) were investigated. The influence of temperature and S/C on hydrogen production was investigated by thermodynamic analysis. The transient characteristics of banana peel steam gasification were investigated by monitoring the evolutionary behavior of syngas production. An increase in S/C can lead to an increase in the selectivity of CO₂, but excess steam (S/C > 21.7) causes a decrease in H₂ yield and CCE. The increase of temperature is beneficial to the increase of CCE, but which leads to a decrease in CO₂ selectivity. When S/C = 27.1, the effect of temperature on H₂ yield can be divided into CCE control region and CO₂ selectivity control region. At temperature < 1023 K, H₂ yield is more sensitive to the changes of CCE. While at temperature > 1023 K, CO₂ selectivity has a more significant effect on H₂ yield. When S/C = 21.7 and temperature is 1023 K, the yield of H₂ produced from the fresh banana peel gasification reaches the maximum value (76.1 ml/g).

H2 and Syngas Production From Catalytic Cracking of Pig Manure and Compost Pyrolysis Vapor Over Ni-Based Catalysts

Catalytic cracking of volatiles derived from wet pig manure (WPM), dried pig manure and their compost was investigated over Ni/Al2O3 and Ni-loaded on lignite char (Ni/C). Non-catalytic pyrolysis of WPM resulted in a carbon conversion of 43.3% and 18.5% in heavy tar and light tar, respectively. No tar was formed when Ni/Al2O3 was introduced for WPM gasifi cation and the gas yield signifi cantly reached to a high value of 64.4 mmol/g at 650oC. When Ni/C was employed, 5.9% of carbon in the light tar was found at 650oC, revealing that the Ni/C is not active enough for cracking of tarry materials. The pyrolysis vapor was cracked completely and gave a H2-rich tar free syngas in high yield. High water amount of WPM promotes steam gasifi cation of char support, causing the deactivation of Ni/C. Such a study may be benefi cial to the development of livestock manure catalytic gasifi cation technology.

An environmental friendly animal waste disposal process with ammonia recovery and energy production: Experimental study and economic analysis

Animal manure waste is considered as an environmental challenge especially in farming areas mainly because of gaseous emission and water pollution. Among all the pollutants emitted from manure waste, ammonia is of greatest concern as it could contribute to formation of aerosols in the air and could hardly be controlled by traditional disposal methods like landfill or composting. On the other hand, manure waste is also a renewable source for energy production. In this work, an environmental friendly animal waste disposal process with combined ammonia recovery and energy production was proposed and investigated both experimentally and economically. Lab-scale feasibility study results showed that 70% of ammonia in the manure waste could be converted to struvite as fertilizer, while solid manure waste was successfully gasified in a 10kW downdraft fixed-bed gasifier producing syngas with the higher heating value of 4.9MJ/(Nm³). Based on experimental results, economic study for the system was carried out using a cost-benefit analysis to investigate the financial feasibility based on a Singapore case study. In addition, for comparison, schemes of gasification without ammonia removal and incineration were also studied for manure waste disposal. The results showed that the proposed gasification-based manure waste treatment process integrated with ammonia recovery was most financially viable.

Steam gasification of acid-hydrolysis biomass CAHR for clean syngas production

Main characteristics of gaseous product from steam gasification of acid-hydrolysis biomass CAHR have been investigated experimentally. The comparison in terms of evolution of syngas flow rate, syngas quality and apparent thermal efficiency was made between steam gasification and pyrolysis in the lab-scale apparatus. The aim of this study was to determine the effects of temperature and steam to CAHR ratio on gas quality, syngas yield and energy conversion. The results showed that syngas and energy yield were better with gasification compared to pyrolysis under identical thermal conditions. Both high gasification temperature and introduction of proper steam led to higher gas quality, higher syngas yield and higher energy conversion efficiency. However, excessive steam reduced hydrogen yield and energy conversion efficiency. The optimal value of S/B was found to be 3.3. The maximum value of energy ratio was 0.855 at 800°C with the optimal S/B value.

Catalytic reforming of nitrogen-containing volatiles evolved through pyrolysis of composted pig manure

The pyrolysis of pig compost was performed in a two-stage fixed-bed reactor to determine the effects of decomposition temperatures and catalysts (i.e., transition-metal and non-transition-metal catalysts) on carbon and nitrogen conversions. The secondary decomposition was investigated at different temperatures from room temperature up to 750°C. Then the effects of various catalysts were investigated at 650°C. Approximately 60% of the carbon and 80% of the nitrogen in the pig compost were converted into volatiles during pyrolysis. Conversion of carbon and nitrogen species in tar into gas, and the evolution undesirable NH3 and HCN without catalyst increased with increasing decomposition temperature. Transition-metal catalysts showed excellent activity for conversion of condensable volatiles into gas and NH3 and HCN into N2. Although non-transition-metal catalysts had moderate activity for the conversion of volatiles into gas and negligible activity for the conversion of NH3 into N2, dolomite can provide liquid fuel with negligible amount of nitrogen species.